Date: Tue, 24 Nov 1998 00:22:30 -0500 (EST) From: Simon Shapiro <shimon@simon-shapiro.org> To: Mike Smith <mike@smith.net.au> Cc: freebsd-alpha@FreeBSD.ORG Subject: Re: UnAligned Access, but why? Message-ID: <XFMail.981124002230.shimon@simon-shapiro.org> In-Reply-To: <199811240213.SAA01690@dingo.cdrom.com>
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Mike Smith, On 24-Nov-98 you wrote:
> > Am trying to get the DPT driver running on alpha.
> > Narrowed down the problem to this:
> >
> > In sys/alpha/include/bus.h there is a series of static inline functions
> > to
> > do the equivalient of inb, inw, and inl, as well as outb, outw, outl.
> > they
> > are called bus_space_{read,write}_[124].
> >
> > The bus_space_read_[14] are causing unaligned access panics. These
> > panics
> > can be eliminated by casting explicitly:
>
> Don't do this. Align the objects you're trying to transfer instead.
Thanx, but how? I took the CAM driver as is and just triesd to actually
align the data. It makes no difference at all. I am still getting the
panics. If you look again at my example (the one following the casts), you
will see that it does not help.
Also (forgive my ignorance here), different PCI busss appear to have
different sizes for the same thing. Or, at least this is how all this
bus_rea/write stuff tries to imply.
The end result is a mass confusion on my part. i am trying to fit the
driver into the existing framework, not change the framework (unless
obviously broken). I do not have enough information to suggest anything is
broken, except the panics.
I may need some detailed help here....
Simon
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